1. Field of the Invention
This invention relates to hydrophilic siloxane copolymers and to a process for preparing them.
2. Background Art
U.S. Pat. No. 5,001,210 describes a method of producing polyurethanes wherein telechelic amino-functional siloxanes, after reaction with cyclic carbonates, are converted with di- or polyisocyanates into the target products. Polyethers are used in the form of diamino polyethers, which are costly compared with polyether diols and monols.
EP-A 1 178 069 describes the preparation of polyether urethane intermediates by reaction of alkenyl polyethers with diisocyanates followed by addition thereto of silanes bearing hydrolysis-sensitive groups. Siloxane chain polymers are not obtainable in this way.
Branched polyether siloxanes are known from Chemical Abstracts 136: 38808. Hydrogensiloxanes are simultaneously reacted with divinylsiloxanes and allyl polyethers. Excess polyether remains unreacted in the product mixture. The products are used as textile softeners and are free of urethane and urea groups.
US 2003/0032726 and its equivalent WO 02/088209 describe a reaction product of (A) polyisocyanate, (B) silicone having a dimethylpolysiloxane segment and one or more isocyanate-reactive groups, (C) a reactant having one or more isocyanate-reactive groups and one or more ionizable groups, and (D) optionally, an organic substance having one or more isocyanate-reactive groups but no ionizable groups, and (E) a compound providing a counterion for the ionizable groups, wherein either the silicone (B) or the reactant (C), or both, have a single isocyanate-reactive group.
US 2003/0032751 describes a reaction product of (A) a polyisocyanate, (B) a silicone having a dimethylpolysiloxane segment and one or more isocyanate-reactive groups, (C) a reactant having one or more isocyanate-reactive groups and one or more ionizable groups, and (D) optionally, an organic substance having one or more isocyanate-reactive groups but no ionizable groups, and (E) a compound providing a counterion for the ionizable groups, wherein the average molecular weight of the reaction product is in the range from 600 to 20,000.
The chief purpose of introducing such ionizable groups is to increase the compatibility of the resulting siloxane copolymers with aqueous systems. The state of the art preference is for ammonium groups and especially quaternary ammonium groups (known as quat groups) to be employed as ionizable groups in the case of textile or cosmetic applications, since they interact particularly well with the respective weakly negatively charged substrate surfaces and so are able to lead to improved substantivity and improved laundering durability. The class of quat-functional siloxane-polyether copolymers in WO 02/10256 A1, WO 02/10257 A1, WO 02/10259 A1 and WO 03/078504 A1 may be mentioned here by way of example. However, compounds disclosed in the references cited all are only obtainable via costly and inconvenient multistage syntheses, have merely satisfactory substantivity and possess only limited durability to laundering. In particular, however, the compounds previously cited do not have any self-dispersing properties. The instability of the corresponding aqueous emulsions to basic conditions and also to the action of high mechanical agitation of the kind occurring with state of the art jet systems, for example, may only be counteracted through addition of large amounts of surfactants and/or salts of polyvalent cations, such as Al2(SO4)3.18H2O, MgCl2.6H2O or the like (WO 03/095735 A2).